Cells exposed to elevated temperatures respond by synthesizing heat shock proteins (HSP). This same set of proteins is also synthesized in response to other stressors: heavy metal ions, anoxia, or some toxic agents. The expression of HSP is thought to represent an adaptive and protective response of cells under stress. This project has two objectives: i) to determine the HSP response of testicular somatic cells (Sertoli and Leydig cells) to known inducers of HSP in other cell types; and 2) to evaluate HSP secretion after exposure in vitro to toxicants known to affect the testis in vivo. In the latter effort is successful, the secretion of HSP in the testis in vivo after insult will be characterized to evaluate HSP as markers of toxicant-induced testicular injury. Ultimately, this project investigates the possibility of using HSP as a set of in vivo markers which would indicate that the testis has been injured.